CHICAGO - A federal bankruptcy judge threw out a disputed new five-year contract between United Airlines and its pilots Friday, dealing the bankrupt carrier a significant setback in its efforts to lock in lower labor costs without a court order.

The contract, which called for 15 percent pay cuts, drew opposition from labor groups and others who complained that it would pave the way for United to eliminate traditional pension plans.

Bankruptcy Judge Eugene Wedoff said several aspects of the proposed agreement would ``unduly tilt the bankruptcy process,`` including the requirement that other unions` pension plans also be terminated.

Wedoff said he hopes the company and pilots can craft a contract based on the previous one, but he warned that he would also reject any future agreement that was tied to the elimination of other unions` pensions, saying those should be considered on their own merits.

``I come to this decision with extraordinary reluctance,`` Wedoff said, citing the pilots` efforts to craft an agreement and the sacrifices they have already made.

The decision was a disappointment for United, spokeswoman Jean Medina said.

``We think we had an agreement that was fair and equitable,`` Medina said. ``But as the judge indicated, we`re going to sit back down at the table.``

The decision comes as the airline industry`s relentless drive to slash costs is leaving employees with a bleak financial outlook.

Machinists at US Airways Group Inc., the nation`s seventh-largest carrier, face pay cuts of up to 35 percent and the loss of thousands of union jobs after a bankruptcy judge Thursday unilaterally canceled their contract.

In that case in Virginia, U.S. Bankruptcy Judge Stephen Mitchell said he had to decide ``which is worse _ that half of the mechanics lose their jobs or all of the mechanics lose their jobs? ... The ultimate question is whether there are going to be any jobs left at the end of the day.``

Tommie Hutto-Blake, president of the Association of Professional Flight Attendants, said the judge`s decision ``should send a chill up the spine of every working American in this country of ours.``

Fifth-ranked Continental Airlines Inc. also said in a regulatory filing Thursday that it needs $500 million in wage and benefit reductions by Feb. 28 or it will face a liquidity crisis.

US Airways, Continental, United and other carriers are struggling to cope with a combination of higher fuel costs, relentless price competition and the growth of low-cost carriers such as JetBlue and Southwest. The Air Transport Association estimates, based on Department of Transportation data, that all U.S. carriers spent an additional $6 billion for jet fuel in 2004, an almost 40 percent increase.

United, a unit of Elk Grove Village, Ill.-based UAL Corp., has said it needs $725 million in annual labor cost reductions in place by mid-January in order to be able to line up the financing needed for it to emerge from Chapter 11 bankruptcy.

The pilots` proposed contract would have allowed the union to terminate the deal if United allowed any other employee group to keep its pension program. If United broke its agreement with the pilots, it could have cost the company $28 million a month _ $14 million in forgone cost savings and $14 million in penalties _ under terms of the deal.

United attorney James Sprayregen contended the pilots` agreement would not dictate future collective bargaining with its other unions.

``I don`t see in any way, shape or form that this impinges our ability to negotiate with each individual union,`` Sprayregen said.

Some creditors also were critical of the pilots` deal, including the federal Pension Benefit Guaranty Corp., which estimates it would be responsible for about $1.4 billion of the plan`s $2.9 billion in underfunded assets if the proposed agreement is approved.

Outside the courtroom, contract negotiations continued Friday between United and unions representing its flight attendants and mechanics.

Barring last-minute agreements with all three unions whose contracts remain unresolved, a bankruptcy court trial was set to begin later Friday on United`s motion to toss out existing labor contracts and have its own terms imposed. That hearing could continue all next week before the judge issues his verdict.

Thursday, Wedoff approved United`s emergency motion to temporarily cut wages by 11.5 percent for baggage handlers, ramp workers and public-contact workers represented by the International Association of Machinists and Aerospace Workers.

IAM said it welcomed the short-term contract, which lasts through April 11, as a way to give it ``the additional time to achieve an agreement that preserves our pensions.``

United planned to have CEO Glenn Tilton testify Friday on the need to slash wages and benefits further and eliminate defined-benefit pensions after nearly five years of steep losses. The company says it was forced to do so by record jet fuel costs, a glut of industry capacity and air fares at a 12-year low.